Hitherto, a portable radio device having the foregoing collapsible structure generally has a mechanism for openably and closably joining an upper enclosure to a lower enclosure by means of a hinge section and can assume two states; namely, an open state and a closed state. A portable radio device having such a structure includes; for instance, portable radio devices described in connection with Patent Document 1 and Patent Document 2. The portable radio device described in connection with Patent Document 1 is openable and closable in its longitudinal direction (vertical direction), and the portable radio device (a portable information processing device) described in connection with Patent Document 2 is openable and closable in two directions including a longitudinal direction and a lateral direction (a horizontal direction). The portable radio device described in connection with Patent Document 1 has an enclosure dipole structure including a conductive metal frame provided on an upper enclosure. The portable information processing device described in connection with Patent Document 2 has an external antenna (a so-called whip antenna) structure.
Patent Document 1: JP-A-2005-006096
Patent Document 2: JP-A-2003-060759